🔍 Key Concepts
• Line-of-sight propagation vs. ground-wave and sky-wave propagation
• Typical frequency ranges for VHF (Very High Frequency), UHF (Ultra High Frequency), and microwave
• How higher frequencies interact with the earth’s curvature and the ionosphere
💭 Think About
• Which types of radio waves are mostly limited to line-of-sight between antennas rather than bending around the earth?
• What are the standard ITU frequency ranges (in MHz) for VHF, UHF, and microwave, and do they mainly use line-of-sight propagation?
• Does the numerical range 50–30,000 MHz line up with the overall region where line-of-sight is the dominant mode of propagation?
✅ Before You Answer
• Know the approximate MHz ranges of VHF (30–300 MHz), UHF (300–3,000 MHz), and microwave (above ~1,000 MHz)
• Confirm which propagation mode (ground-wave, sky-wave, or line-of-sight/space-wave) is dominant in the VHF and higher bands
• Check if the given MHz range in one choice covers mainly the same bands as the specific groups of frequencies named in another choice